Signal storing device and proportional-control circuits therefor



Oct. 2, 1951 H. ZIEBOLZ 2,569,911

SIGNAL STORING DEVICE AND PROPORTION/XL CONTROL CIRCUITS THEREFOR FiledDec. 18, 1944' 2 Sheets-Sheet 1 U] Q 5 O HERBBSRT ZIEBOLZ Guam,

Oct. 2, 1951 oLz 2,569,911

' H. ZlE SIGNAL STORING DEVICE AND PROPORTIONAL CONTROL CIRCUITSTHEREFOR Filed Dec. 18, 1944 2 Sheets-Sheet 2 HERBE T 21325011 WW @MWPatented Oct. 2, 1951 SIGNAL STORING DEVICE AND PROPOR- TIONAL-CONTROLCIRCUITS THEREFOR Herbert Ziebolz, Chicago, Ill., assignor toElectronbeam, Ltd., Chicago, 111., a partnership of Illinois ApplicationDecember 18, 1944, Serial No. 568,751

15 Claims. 1

This invention relates to signal storing devices by which signals may bestoredor recorded, and to regulating systems of the proportional controltype incorporating such signal storing devices.

The signal storing device of my invention is also useful as a time delaycircuit.

Another use for the invention is for integrating the effect of a signalor force acting over a certain time.

My invention involves a photocell circuit which receives light from anormally constant source, and a light modulating device interposedbetween the cell and the source to vary the light transmitted to thecell in accordance with a controlling signal or force. The lightmodulating device is formed of a normally transparent substance whichwhen subjected to certain forms of radiant energy from the signal sourcebecomes opaque or clouded to a varying degree depending upon theintensity of the radiant energy and the time during which the radiantenergy is acting on the slibstance. The invention also involves a sourceof radiant energy for acting on the substance of the light valve toerase the opacity or to restore the substance to its original condition.

In certain respects my signal storage device acts in the same manner asan electric condenser in being charged through a resistance, that is,when an input signal of a given value is applied to the device, theoutput voltage increases with time and in proportion to the value of theinput signal, in a manner similar to the increase in voltage across acondenser which is being charged through a resistance by a givencurrent. When the restoring energy is applied to the storage device, theaction is somewhat like a condenser being discharged through aresistance circuit. The time required for the output current or voltageto drop to zero is dependent upon the intensity of the restoring energyand on the time during which the energy is applied.

My signal storing devices are capable of many uses but are especiallyuseful in regulating systems of the proportional control type, as willappear hereinafter.

The invention is illustrated in the accompanying drawing in which Figure1 is a diagrammatic showing form of the storage device;

Figure 2 is a set of curves illustrating the operation of Figure l;

Figure 3 is a diagram illustrating a modified form 01' the storagedevice;

of one Figure 4 is a diagrammatic showing of a pressure regulator systemof my invention employing the storage device; and

Figure 5 is a diagrammatic showing of a speed regulating system usingthe storage device, which constitutes another embodiment of myinvention.

Referring to the drawing, l indicates an electron discharge tube whichembodies a suitable electrode arrangement for producing a, beam ofelectrons originating at cathode 2 and being directed upon an electronsensitive layer 3 formed on the front face of a transparent plate 3a.The intensity of the electron beam is controlled by a grid 4 thepotential of which is varied in accordance with signals applied to inputterminals 5. In the absence of input signals the electron beam is cutoff by a negative potential applied to the grid from a suitable biasingsource 4a.

The electron sens1tive layer 3 is formed of a crystalline substanceselected from the alkali and alkali earth halides, such as thechlorides, bromides and iodides of sodium and potassium, lithiumbromide, calcium fluoride, strontium fluoride and strontium chloride.Preferably a mixture of potassium bromide and potassium hydride isemployed in proportions of 1000 to 1. This mixture becomes black or darkblue under the influence of fast electrons.

The light sensitive element may be formed of a single fiat crystal, inwhich case there will be no need for the plate 3a, or it may be formedas a mosaic of small crystals or as a micro-crystalline layer.

6 indicates a source of normally constant light from which a beam ofrays is collected by an optical condenser 7 and directed through asuitable heat filter 8 onto the electron sensitive layer 3. The rayswhich pass through the light valve are collected by a condenser 9 andare directed upon a photocell in which is included in the input circuitof a vacuum tube amplifier H.

The photocell is connected in the input circuit of the amplifier bymeans of a coupling resistance l2 which is connected in series with thecell through a battery l3. A source of biasing voltage I is alsoinserted between the cathode and the grid of tube II. The plate circuitof tube ll includes a source of potential l5 and a coupling resistance[6 in series. One output terminal Ila is connected to the plate of tubeII and the other terminal [1b is connected to a movable contact onpotentiometer l8 connected in shunt to source 15. With full light oncell In and no signal applied to input terminals 5, potentiometer I8 isadjusted until there is no output voltage across terminals l'la-Ilb.

Operation of Figure 1 is as follows: Normally the layer 3 is transparentand the maximum light falls on cell In which results in zero outputvoltage at terminals llallb. When a signal of predetermined intensity isapplied to input terminals 5, the layer 3 will be bombarded 'byelectrons of an intensity determined by the value of the signal. Thisbombardment causes the layer to become increasingly opaque in accordancewith the intensity of the electron bombardment and the time during whichthe bombardment acts. Thus, the output voltage of the amplifier willincrease with time and in proportion to the value of the input signal.

The set of curves shown in Figure 2 will illustrate the operation ofFigure l. The horizontal axis to the right of the origin is expressed interms of e a: t where e is the value of applied signal and t is the timeduring which the signal acts. The vertical axis above the origin iscalibrated in terms of transparency of 'the layer 3. The horizontal axisto the left of the origin is calibrated in terms of light falling on thecell l0, and the vertical axis below the origin is calibrated in termsof voltage at the output terminals of the storage device. Curve A showsthe relation between the at value and the transparency of the layer 3.Curve B shows the relation between the transparency of the layer 3 andthe light received by the cell l0, while curve C indicates the relationbetween the light acting on cell and the voltage at the outputterminals. Thus, where the ct product has a value equal to a, the outputvoltage has a value equal to a and may be determined by drawing thedotted lines through the three curves as shown in Figure 2 starting fromthe point a. In a like manner, where the ct product has a value b, theoutput voltage will have a value I). From Figure 2 it will be seen thatas the ct product increases, the output voltage also increases.

The layer 3 will retain its semi-transparent or opaque condition evenafter the signal ceases to act, and the voltage at the output terminalswill continue to be effective unless the transparency of the layer isrestored. Depending on the nature of the layer 3, the transparency maybe restored by heating the layer or by subjecting it to the action ofradiant energy of a different wave length from that of source 6. InFigure l I have shown a source of infra-red radiation represented by theelectric light [8 energized from a suitable source 19 through anadjustable resistance 20. Rays from the source It! are collected by anoptical system H and projected upon the layer 3. The time required torestore transparency of the layer will be dependent upon the intensityof the erasing rays. Thus, the time required for the output voltage todie down to zero after discontinuance of the input signal will dependupon the value of the erasing energy and may be varied by changing thevalue of this energy.

Instead of controlling the intensity of the electron beam bombarding thelayer 3, suitable beam deflecting means such as deflecting plates 22 and23 may be energized normally to deflect the beam to one side of thelayer 3, and the input signal would be impressed upon the deflectingmeans to deflect the beam onto a varying portion of the layer 3depending on the strength of the signal.

Instead of arranging the cathode ray tube so that the beam is cut off inthe absence of a signal, the grid 4 may be biased normally to apotential such that the beam has an intensity of a given value and inputsignals of one polarity will increase the intensity of the beam whilesignals of opposite polarity will decrease the intensity ot the beam. Inthis case also, the outut potentiometer will be adjusted to produce zerooutput voltage in the absence of signals, and the output voltage willvary in polarity in accordance with the polarity of the input signal.

In most cases, and especially where the material is in the form 0! asingle crystal, the opacity of the material seems to be due to an opaquedeposit within the crystal structure which can be caused to move withinthe crystal by the application of an electric field. Further more theopaque deposit can be made to disappear by subjecting the crystals to anelectric field at a suitable temperature, the deposit being drawnthrough the crystal towards the positive pole producing the field and itthereupon disappears leaving the crystal substantially transparent. Thespeed of movement of the deposit depends upon the strength 01' theelectric field and upon the temperature 01' the crystal, and this speedmay be varied by varying either the field or the temperature. For agiven strength of field, the movement increases with increase intemperature of the crystal.

In Figure 3 I have shown an arrangement in which the opaque deposit iserased or removed by means of an electric field instead of by infra-redrays as in Figure 1. In this arrangement, the light valve consists of aflat crystal 3 formed of an alkali halide such as potassium chloride andis provided with a pair of thin metallic electrodes 3b and 30 onopposite faces thereof. These electrodes are formed 0! thin transparentmetallic layers deposited in any suitable manner, but they may also beformed 01 line wire netting or mesh. The electrodes 3b and 3c aremaintained at a difference of potential from a suitable sourcerepresented by the battery 24. This potential may be adjusted by meansof a potentiometer Ila.

Figure 3 also illustrates a further variation of Figure l in thatinstead of using electrons to produce the opaque deposit within thecrystal, light rays of a dlfierent wave length from the source 6 areemployed for this purpose. For example, a vapor lamp 25 is employed toprovide a source of light of lower wave length than the source I, whichmight conveniently be formed of an incandescent lamp producing a. longerwave length than the source 25, and if necessary, suitable filters maybe interposed between the two sources to limit the radiations to thedesired separated bands. The lamp 2! may be suitably energized ormodulated by applying the input sig nal to the terminals 5. A lenssystem 23 collects rays from the source 25 and directs them against thefront face of crystal 2 which causes the opaque deposit to be formed onthe front face of the crystal in accordance with the intensity of therays from the source 25. The voltage applied between transparent plates3b and 3c causes this deposit to travel through the crystal towards theplate 3b, and the time required to pass through the crystal is dependentupon the potential diiference maintained between the two plates and onthe temperature of the crystal. As soon as the deposit reaches thepositive pole 3b it disappears and the crystal is restored to itsoriginal transparency, assuming that no signal is impressed on terminalsI. The operation 0! the photocell circuit is the same as in the case 0!Figure 1.

ing a movable shutterfla which cuts oil a varying amount of therayswhich fall upon the crystal 3 from the source 25. The shutter 21a may bepositioned normally so that for zero signal it either shuts off thelight from source 23 or admits the light fully. In either case,potentiometer I3 01' the amplifier would be adjusted to obtain acondition of no output voltage for no input signal.

From the foregoing it is clear that the arrangements shown in Figures 1and 3 are useful in various applications requiring delayed action of arelay, or in situations requiring a storage effect such as that obtainedin an ordinary condenser.

' Also, these devices will be useful in certain applications in thecontrol fleld where it is desirable to have the stored signal disappearas a function of time.

In Figure 4 I have shown one application of devices of the type shown inFigures 1 and 3 as applied to a system for regulating the flow oi fluidsin a conduit. In this arrangement, 23 indicates a supply pipe forsupplying fluid, such as gas or liquid, under pressure to any suitableapparatus which requires a constant pressure of the fluid supply. Itwill be understood that the fluid pressure supplied to the apparatus issubject to change, either by reason of changes in the pressure of thesource of fluid or by changes in the consuming apparatus, and theproblem is to maintain a constant pressure at the intake of theapparatus. For the purpose of regulating the pressure a control valve 29is positioned in the pipe 28 and a suitable pressure responsive device30 is connected to the pipe 23 between the valve 29 and the consumingapparatus. The device 30 responds to the pressure in the pipe 23 andproduces a direct current or voltage in its output circuit 30aproportional to the pressure applied to the device. Such devices arewell known and the details need not be described. The current producedby device 39 is employed to control the deflection oi the beam of thecathode ray tube.

The cathode ray tube may be of any known construction but for thepurpose of illustration it consists of an insulating envelope 3|enclosing an electron gun structure represented at 32 which supplies anelectron beam which passes through a perforated anode 33 which ismaintained at a positive potential with respect to the gun. The cathoderay beam is represented by the dotted lines 34 and is directed towardstarget anodes 35 and 36 positioned in the opposite end of the tube fromthe gun 32. Anodes 33 and 33 are maintained at a positive potential byconnections to a suitable source through coupling resistances 31 and 33.Beam deflecting means represented by coil 39 is provided for fixing theinitial position of the beam, and this coil is energized by anadjustable current from a suitable source represented by battery 40through resistance 4|. The output of pressure responsive device 33 isconnected to energize a second beam deflecting means represented by thecoil 42, and this coil tends to deflect the beam in the oppositedirecdeflecting means tend to shift the beam 34 from one target anodetowards the other, and vice versa.

So long as the electron beam falls between the target anodes, or wherethe beam falls upon the two anodes in equal amounts, there will be nodifference of potential between the two anodes. If, however, one targetanode intercepts more electrons from the beam than the other, then adiflerence of potential develops between the anodes, and the polarity ofthe output voltage .ed November 9, 1948. It will be understood that therelay 44 controls the motor for operation in one direction for onepolarity of output signal and in the opposite direction for a signal ofopposite polarity, and the speed of the motor will be proportional tothe value of the signal.

Motor 43 is connected to operate the control valve 29 through anysuitable driving mechanism such as that represented by a worm 45 mountedon the motor shaft and serving to drive a wormwheel 46 carried by theshaft of valve 29. A small pilot generator 41 having a field winding 43is also driven by motor 43. The generator 41 is connected to the inputterminals 5 of a signal storage device like that shown in Figures 1 or 3and represented by the rectangle 49. The output terminals of the storagedevice are connected to energize a deflecting coil 50 associated withthe cathode ray tube. The storage device is adjusted to receive signalsof either polarity as described above.

Operation of Figure 4 is as follows: Resistance 4| is adjusted todetermine the value of the pressure to be maintained at the inlet of theconsuming apparatus. Coil 39 tends to deflect the electron beam in adirection to operate motor 43 to open the valve 29. As the pressuresupplied to the consuming apparatus builds up, the current in deflectingcoil 42 produced by device 30 increases and tends to deflect theelectron beam in an opposite direction. As soon as the pressure reachesthe desired point, the beam 34 has been deflected back to its central ornormal position. The beam will remain in this position so long as thepressure remains at the desired value, but if the pressure varies fromthis value for any cause, there will be a change in current supplied tocoil 42, and the beam will be deflected in a direction to energize motor43 and operate valve 29 in a direction to restore the pressure to thedesired value. As motor 43 begins to operate, pilot generator 41generates a voltage of a value proportional to the speed of the motorand o! a polarity determined by the direction of rotation. This voltageis repeated through storage device 49 and energizes deflecting coil 50in a direction tending to restore the beam 34 to its neutral position.The operation of motor 43, through the action of valve 29 and pressureresponsive device 30, changes the amount of current supplied to coil 42in a direction tending to restore the beam to its normal or neutralposition. As the motor continues to operate, and as the pressure aptionfrom coil 39. It will be understood that both 7 preaches the desiredvalue, the speed of the motor will slow down, thus reducing the value ofthe control potential applied to the input of storage device 49, but dueto the time delay action of this device, the change is not immediatelyefifective in coil 50. Accordingly, the motor speed will be relativelyhigh at the beginning of the adjustment for any given departure of thecondition from its normal value, and the speed will decrease as thevalue of the condition approaches the normal value. The current in coil50 tends to restore the beam to its neutral position and it tends tostop the motor 43 earlier than it would be stopped by the action of coil42 acting alone. This action tends to prevent overshooting of theregulator. Furthermore, the current supplied to coil 50 is proportionalto the speed of motor 43 and to the time of operation of the motor; inother words, the current in coil 50 will be proportional to the amountof movement of the valve 29 from an initial position. This current,however, will decrease to zero in a predetermined time after the motorstops depending upon the strength of the restoring energy applied to thestoring device 49. The gradual reduction in the value of the current incoil 50 also tends to stabilize the action of the regulator system andprevents droop in the regulation as Well as preventing hunting.

In case the pressure at the inlet of the consuming device should changein an opposite direction from that described above. the motor 43 will bedriven in an opposite direction, and the voltage supplied to deflectingcoil 50 will also be reversed in direction, and the regulating actionwill be the same as that described above.

The regulator system shown in Figure is generally like that shown inFigure 4, and like parts are represented by the same reference numerals.In this case the conduit 28 is a steam supply pipe for a steam turbine5| the speed of which is to be maintained constant. For this purpose thecounter-deflecting coil 42 is energized from a pilot generator 52 drivenby the turbine 51. An additional deflecting coil 53 is provided and isenergized directly from pilot generator 47. The deflecting coil 58 isenergized from storage device 49 which has its input terminals connectedto generator 4'1 through potentiometer 54. In this case also, thestorage device 49 is adjusted to receive signals of both polarity. Coil53 pro vides a restoring action directly proportional to the speed ofmotor 43, while coil 53 provides a restoring action proportional to theproduct of motor speed and time.

The operation of Figure 5 will be clear from the foregoing descriptionof operation of Figure 4. Coil 53 is responsive directly andinstantaneously to the voltage generated by pilot generator 47, and actsin a direction tending to restore the electron beam to its neutralposition. I he current supplied to coil 53 is proportional to the speedof motor 43. Coil 59 is energized in the same manner as for Figure 4;that is, the current in this coil is proportional to the amount ofmovement of the valve 29 from its initial position, but the current inthis coil dies down to zero value in a predetermined time after stoppingof the motor. It may be noted that the current in coil 53 ceases flowingas soon as the motor stops running, but the current in coil 53 continuesfor a time after the motor stops.

An additional feature which may be embodied in the regulator systems ofFigures 4 and 5 is the control of the rate of restoring action withinthe storage device in accordance with the position of the controllingvalve. For example, as shown in Figure 5, the intensity of the erasingor restoring energy supplied by source It! may be varied in accordancewith the position of the valve by placing the movable contact forresistance 20 on the driving gear 46 for the valve 29. Since theposition of valve 29 forms a rough indication of the value of the load,the arrangement just described will provide means for varying therestoring rate of storage device 49 in accordance with the value of theload.

I claim:

1. A signal storing and integrating device comprising a light sensitivecircuit including a light sensitive cell, a source of light forenergizing said cell, a light transmitting element interposed betweensaid source 01' light and said cell and comprising a substance whichunder the influence of radiant energy is rendered opaque to a degree inproportion to the intensity of the radiant energy and the time theenergy acts on said substance, a source of radiant energy for cloudingsaid substance, and signal responsive means for varying the amount ofclouding radiant energy acting on said substance.

2. A device according to claim 1 wherein said signal responsive meansincludes intensity control means responsive to said received signal tovary the intensity of energy from said clouding source acting on saidlight transmitting substance.

3. A device according to claim 1 wherein said signal responsive meansincludes direction control means responsive to said received signal todirect clouding radiant energy from said clouding source over a variableportion of said light transmitting substance.

4. A device according to claim 1 and including means constantly actingon said light transmitting substance and tending to restore thetransparency of said substance at a predetermined rate.

5. A device according to claim 1 and including a source of radiantenergy constantly acting upon said light transmitting substance andserving to restore the transparency of said substance in proportion tothe intensity of said restoring energy and the time of action thereof.

6. A signal translating device for producing an electric current of avalue proportional to the product of the magnitude of an input signaland the duration of the signal comprising, in combination, a lightsensitive circuit including a light sensitive cell, a source of lightfor energizing said cell, a light transmitting element interposedbetween said source of light and said cell and comprising a substancewhich under the influence of radiant energy is clouded to a degree inproportion to the intensity of the radiant energy and the time theenergy acts on said substance, 9. source of radiant energy for cloudingsaid substance, an input circuit for said device including signalresponsive means for varying the amount of clouding radiant energyacting on said substance, and an output circuit connected to spacedpoints of said light sensitive circuit having the same potential atno-signal condition.

'7. In a regulator system, the combination of a movable control elementfor varying the magnitude of a condition to be regulated, means foroperating said control element including an electron beam relay havingbeam defiecting means operable to deflect the beam of said relay to oneside or the other of a normal position for said beam at which saidcondition has a predetermined value, and means responsive to saiddeasoaou flection to move said control element in one direction or theother to increase or decrease the magnitude of said condition, meansresponsive to variation oi said condition from said predetermined valuefor actuating saidbeam deflecting means in a direction to restore saidcondition to said predetermined value, means responsive to movement ofsaid control element for applying an opposing beam-deflecting forceproportional to the amount of movement of said control element from itsinitial position, and means for reducing said opposing force to zero ata predetermined rate after said element stops moving.

8. m a regulator system, the combination of a movable control elementfor varying the magnitude of a condition to be regulated, means foroperating said control element including an electron beam relay havingbeam deflecting means operable to deflect the beam of said relay to oneside or the other of a normal position for said beam at which saidcondition has a predetermined value, and means responsive to saiddeflection to move said control element in one direction or the other toincrease or decrease the magnitude of said condition, means responsiveto variation of said condition from said predetermined value ioractuating said beam deflecting means in a direction to restore saidcondition to said predetermined value, and means for applying to saidbeam relay an opposing deflecting force proportional to the product ofthe speed of movement of said element and the duration of movement,including means for continuing said opposing force after movement ofsaid element has stopped but at a continuously decreas-v ing value.

9. In a regulator system, the combination of a movable control elementfor varying the magnitude 01 a condition to be regulated. means foroperating said control element including an electronbeam relay havingbeam deflecting means operable to deflect the beam of said relay to oneside or the other 01' a normal position for said beam at which saidcondition has a predetermined value, and means responsive to saiddeflection to move said control element in one direction or the other toincrease or decrease the magnitude of said condition, means responsiveto variation of said condition from said predetermined value foractuating said beam deflecting means in a direction to restore saidcondition to said predetermined value, means responsive to the speed ofmovement of said control element tending to o posite the deflection ofsaid beam by said condition responsive means, and means for applying tosaid beam relay an opposing deflecting force proportional to the productoi the speed of movement of said element and the duration of movement,including means for continuing said op osing force after movement ofsaid element has stopped but at a continuously decreasingvalue.

10. In a regulator system. the combination of a movable control elementfor varying the magnitude of a condition to be regulated. means foroperating said control element inc uding an electron beam relay havingbeam deflecting means operable to deflect the beam of said relay to oneside or the other of a normal position for said beam at which saidcondition has a predetermined value. and means res onsive to saiddeflection to move said control element in one direction or the other toincrease or decrease the magnitude of said condition. ad ustablemagnitude setting means for energizing said beamdeflectingmeanssoastourgeittomoveinadirection along a line passingthrough said normal position such as'to increase the magnitude of suchcondition, adjustment of said means serving to set the predeterminedvalue, means responsive to the value of said condition and tending todeflect said beam along said line in the opposite direction for thepurpose of limiting the increase in magnitude of said condition, meansresponsive to the speed of movement of said control element tendingtooppose the deflection of said beam by said condition responsive means,and means for applying to said beam relay a defleeting forceproportional to the product of the speed of movement of said element andthe duration of movement and in a direction tending to reduce thedeflection of said beam from its normal position, including means forcontinuing said opposing force after movement of said element hasstopped but at a continuously decreasing value.

11. In a regulator system, the combination oi. a movable control elementfor varying the magnitude of a condition to be regulated, means foroperating said control element including an electron beam relay havingbeam deflecting means operable to deflect the beam of said relay to oneside or the other of a normal position for said beam at which saidcondition has a predetermined value, and means responsive to saiddeflection to move said control element in one direction or the other toincrease or decrease the magnitude 01 said condition, means responsiveto variation of said condition from said predetermined value foractuating said beam deflecting means in a direction to restore saidcondition to said predetermined value, a light sensitive circuitincluding a light sensitive cell, a source of light for energizing saidcell, a light transmitting element interposed between said source oflight and said cell and comprising a substance which under the influenceof radiant energy is clouded to a degree in proportion to the intensityof the radiant energy and the time the energy acts on said substance, asource of radiant energy for clouding said substance, means operated bysaid control element for varying the amount of clouding energy acting onsaid substance in accordance with the speed of said element and meansener ized by the current in said light sensitive circuit for op osingthe deflection of said beam by said condition responsive means.

12. A re ulator system according to claim 11 and including means actingon said li ht trans mitting element tending to restore the transparencyof said element at a predetermined rate.

13. In a regulator system embo ying a movable control element for varyinthe magnitude of a condition to be regulated and includin conditionresponsive means responsive to variation in said condition from apredetermined value, the combination of means for operating said movablecontrol element by said condition res onsive means com rising. anelectron beam tube having beam deflecting means controlled by saidcondition responsive means to deflect the beam of said tube to one sideor the other oi a normal position in response to variation of saidcondition above or below a predetermined value, and including meansresponding to said deflection to operate said control element in adirection tending to restore said condition to said predetermined value,and means for applying to said beam tube an opposing deflecting forcepropor- 11 tional to the product of the speed or movement of saidelement and the duration of movement thereof and tending to opposedeflection 01 said beam from its normal position.

14. In a regulator system embodying a movable control element forvarying the magnitude of a condition to be regulated and includingcondition responsive means responsive to variation in said conditionfrom a predetermined value, the combination of means for operating saidmovable control element by said condition responsive means comprising,an electron beam tube having beam deflecting means energized by saidcondition responsive means, means responsive to the speed or movement ofsaid control element tending to oppose the deflection of said beam bysaid condition responsive means, and means for applying to said beamtube an opposing deflecting force proportional to the product of thespeed of movement or said element and the duration of movement thereofand tending to oppose deflection of said beam from its normal position.

15. In a regulator system embodying a movable control element forvarying the magnitude of a condition to be regulated and includingcondition responsive means responsive to variation in said conditionfrom a predetermined value, the combination of means for operating saidmovable control element by said condition responsive means comprising,an electron beam tube having beam deflecting means energized by saidcondition responsive means, a light sensitive cireuit including a lightsensitive cell, a source of light for energizing said cell, a lighttransmitting element interposed between said source of light and saidcell and comprising a substance which under the influence of radiantenergy is clouded to a degree in proportion to the intensity of theradiant energy and the time the energy acts on said substance, a source01 radiant energy tor clouding said substance, means operated by saidcontrol element for varying the amount 01' clouding energy acting onsaid substance in accordance with the speed of said element and meansenergized by the current in said light sensitive circuit for opposingthe deflection of said beam by said condition responsive means.

HERBERT ZIEBOLZ.

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